This invention relates to organic polymers, particularly organic polymers containing dispersed reinforcing agents.
It is well known to reinforce organic polymers with macroscopic fillers such as glass, polyamide, polyester, graphite or similar fibers; particulate fillers such as calcium carbonate, barium sulfate and the like, and other fillers such as sand, and milled or flaked glass. Although these fillers are known to improve the properties of the polymer, they have several drawbacks. One is the amount of such fillers which are needed to obtain good reinforcement.
Typically, up to about 60 percent or more of the filled polymer comprises the filler material. It would be highly desirable to obtain good reinforcement at lower levels of filler. Another problem is that many of these filler materials do not strongly adhere to the polymer matrix. Accordingly, the reinforcement is not as great as would be expected. Another problem is that although certain properties such as stiffness and tensile strength are improved by the use of these fillers these improvements are usually accompanied by a substantial decrease in other properties, notably impact strength, fatigue and elongation.
The use of fillers is of particular interest in the preparation of polymers from compounds and polymers which contain a plurality of active hydrogen atoms. Principal among these polymers are the polyurethanes and polyureas. In preparing these polymers, it is normally desirable to obtain the best possible physical properties. For example, when a flexible polymeric foam is prepared, it is often desirable to produce a foam which has good load-bearing, resiliency, and tensile properties.
The materials most commonly used in preparing polyurethanes and/or polyureas are polyethers and polyesters which contain two or more active hydrogen-containing groups. Although excellent polymers, both cellular and noncellular, are produced therefrom, it is desirable in certain instances to further improve their properties. One known method of improving the properties of polyurethanes made from polyethers or polyesters is to employ a dispersion of polymer particles in a continuous polyether or polyester polyol phase. These so-called polymer polyols or copolymer polyols contain addition polymers, polyurea or polyurethane-urea particles, or other polymers dispersed through the polyol as a plurality of colloidal (10-1000 nm) particles. The dispersed particles have been shown to improve various properties of the resulting cellular polyurethane and/or polyurea, and often perform a cell-opening function in the production of polyurethane and/or polyurea foam.
However, even with the use of a polymer polyol, improvement in certain properties of the polyurethane and/or polyurea polymer is desired. In particular, it is desirable to provide a cellular polyurethane and/or polyurea having a high modulus as later defined. Such foams are particularly suitable for automobile or other seating, in which the foam desirably feels soft as one sits on it, yet provides sufficient support for adequate comfort.
It would be desirable to provide a reinforced polymer in which good reinforcement is obtained even at relatively low filler levels and in which desirable improvements in physical properties are achieved without major losses in other properties.